Oscilloscope/StripChart Control

Despite the rather vast array of tools that are provided with Visual C++ one area that seems to be somewhat ignored is that which is concerned with graphical data analysis. There seem to be millions of ways of showing, sorting and relating text and numbers but no good ways of graphically displaying them. (In my world, one decent plot is worth a thousand CRichEditCtrl's.) Thus I'm always looking for a better way of graphically presenting information in an easily interpreted manner.

Historically, I've shown "live" gauge readings through the constant updating of a numerical value in a read-only edit control. However, apart from making the user seasick, this approach does not easily reveal subtle patterns or trends. This level of interpretation requires an "oscilloscope" or "strip chart" style display of historical data.

This OscopeCtrl is based on the bitmap shifting concept used in Ken C. Len's Histogram Control. It provides significant enhancements through the display of scaling information and plotting of double precision values. The user implementation is described below.

Call the COScopeCtrl::SetPosition function with the the data value to be appended to the plot. Subsequent calls to SetPosition will continue to shift the plot to the left.

...
m_OScopeCtrl.AppendPoint(nRandom);
...

Other Considerations

A. Color Selection

The OScopeCtrl optimizes the drawing of the plot for the sake of speed and smoothness of animation. In this approach, memory based device contexts and associated bitmaps are constructed for 1.) the underlying grid and 2.) the plot line segments. These two bitmaps are combined in another memory based display context to avoid flicker. During the painting of the control, the grid is BitBlt'd (as a SRCCOPY), the plot is then added by BitBlt'ing it as a "pattern" via SRCPAINT. The result is then BitBlt'd to the display (as SRCCOPY). (See the COScopeCtrl::OnPaint function for details.)

This approach is quite clean and fast for light colored plots and light colored grids which are to be displayed on dark colored backgrounds. For some light colored backgrounds, the plot and/or grid may not be displayed do to the OR'ing nature of the SRCPAINT-style BitBlt.

B. Font Selection

The COScopeCtrl draws the axis information text in a font which is 14 pixels high. The attributes for both the horizontal and vertical fonts can be modified in the COScopeCtrl::InvalidateCtrl() function.

C. Further Customization

The COScopeCtrl constructor sets a most of the default behavior and is thoroughly documented. These values can be modified to achieve different styles of displays.

Try this one for fun.

To give the feel of an old green oscilloscope display, try these settings:

Top White Papers and Webcasts

Live Event Date: March 19, 2015 @ 1:00 p.m. ET / 10:00 a.m. PT
The 2015 Enterprise Mobile Application Survey asked 250 mobility professionals what their biggest mobile challenges are, how many employees they are equipping with mobile apps, and their methods for driving value with mobility.
Join Dan Woods, Editor and CTO of CITO Research, and Alan Murray, SVP of Products at Apperian, as they break down the results of this survey and discuss how enterprises are using mobile application management and private …

The mobile market is white hot. Building a well-crafted product development plan that addresses market research, strategy, design, and development will provide the greatest chance for success. Each phase of an app's lifecycle is critical to the its overall success and feeds into the next step of the process of product development for the app. This white paper examines the five key phases of mobile app creation, one by one, to understand how they work together to help create a successful mobile app.